Igniters are used to provide effective sparks in a combustion chamber of a gas turbine engine. An igniter typically comprises an electrode extending through the center of a cylindrical grounded igniter tube. A ceramic insulating core is located between the electrode and the igniter tube to insulate the electrode and prevent grounding the electrode. The igniter mounts to a diffuser casing surrounding the combustion chamber, and the operative tip of the igniter typically projects slightly into the combustion chamber. When an electrical signal is sent through the electrode, a spark is produced at the operative end which ignites the fuel in the combustion chamber.
A pressure sensor is typically located downstream of the igniter to sense the fluid pressure feeding the combustion chamber. The pneumatic pressure sensor includes a sense tube that extends through the diffuser casing. The tip of the sense tube is located in an annular chamber formed between the diffuser casing and the combustion chamber so that gases feeding the combustion chamber are directed through the sense tube to the pneumatic sensor. Many components are required to mount the pressure sensor to the combustion system. For example, several brackets, fittings and tube assemblies are used to attach the pressure sensor to the combustion system. These components add additional assembly, weight and cost to the gas turbine engine.
An augmenter or afterburner system includes an igniter and pressure sensor similar to a combustor system. The igniter of an afterburner is positioned slightly within the casing wall of a chamber for combustion, and the pressure sensor is positioned in a chamber formed between a diffuser casing and the chamber for combustion. The afterburner system further includes a second pressure sensor to measure the pressure within the afterburner's chamber for combustion. This second pneumatic sensor includes a second sense tube that extends through the diffuser casing and the casing of the chamber for combustion. The tip of the second sense tube is located within the afterburner's chamber for combustion. The second sense tube directs gases from the afterburner's chamber for combustion to the second pressure sensor to determine the burner pressure. The pressure within the afterburner's chamber for combustion is used by the engine control system for several different operations, including controlling the fuel-air mix ratio. Similar to the first pneumatic sensor, many components are required to mount the second pneumatic sensor to the augmenter system. These components add assembly time, weight, and cost to the afterburner system.